Just try to use ElementCollection with Set

Posted on Monday Feb 17, 2014 at 04:25PM in Technology

Just some notes about how it works, how create schemas, and how DMLs executes, and try to find its pros and cons.

Environment

WildFly 8.0.0.Final
Hibernate 4.3.1
PostgreSQL 9.2.4
postgresql-9.3-1100.jdbc41.jar

Example project

Whole project resources are available in GitHub.

Set<Basic>

Schema

jpatest=# \d setbasic
   Table "public.setbasic"
 Column |  Type  | Modifiers 
--------+--------+-----------
 id     | bigint | not null
Indexes:
    "setbasic_pkey" PRIMARY KEY, btree (id)
Referenced by:
    TABLE "setbasic_set" CONSTRAINT "fk_qov1oy3cmf1wmttooahy264eh" FOREIGN KEY (setbasic_id) REFERENCES setbasic(id)

jpatest=# \d setbasic_set
           Table "public.setbasic_set"
   Column    |          Type          | Modifiers 
-------------+------------------------+-----------
 setbasic_id | bigint                 | not null
 set         | character varying(255) | 
Foreign-key constraints:
    "fk_qov1oy3cmf1wmttooahy264eh" FOREIGN KEY (setbasic_id) REFERENCES setbasic(id)

jpatest=#

Entry data

log

13:59:11,377 DEBUG [org.hibernate.SQL] (default task-15) insert into SetBasic (id) values (?)
13:59:11,378 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [1] as [BIGINT] - [1]
13:59:11,379 DEBUG [org.hibernate.SQL] (default task-15) insert into SetBasic_set (SetBasic_id, set) values (?, ?)
13:59:11,379 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [1] as [BIGINT] - [1]
13:59:11,379 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [2] as [VARCHAR] - [hige]
13:59:11,380 DEBUG [org.hibernate.SQL] (default task-15) insert into SetBasic_set (SetBasic_id, set) values (?, ?)
13:59:11,380 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [1] as [BIGINT] - [1]
13:59:11,380 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [2] as [VARCHAR] - [hoge]
13:59:11,381 DEBUG [org.hibernate.SQL] (default task-15) insert into SetBasic_set (SetBasic_id, set) values (?, ?)
13:59:11,381 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [1] as [BIGINT] - [1]
13:59:11,381 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [2] as [VARCHAR] - [fuge]

table

jpatest=# select * from setbasic;
 id 
----
  1
(1 row)

jpatest=# select * from setbasic_set;
 setbasic_id | set  
-------------+------
           1 | hige
           1 | hoge
           1 | fuge
(3 rows)

jpatest=#

Find

14:01:27,838 DEBUG [org.hibernate.SQL] (default task-8) select setbasic0_.id as id1_2_0_ from SetBasic setbasic0_ where setbasic0_.id=?
14:01:27,838 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-8) binding parameter [1] as [BIGINT] - [1]
14:01:27,839 DEBUG [org.hibernate.SQL] (default task-8) select set0_.SetBasic_id as SetBasic1_2_0_, set0_.set as set2_3_0_ from SetBasic_set set0_ where set0_.SetBasic_id=?
14:01:27,840 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-8) binding parameter [1] as [BIGINT] - [1]
14:01:27,839 FINE  [org.nailedtothex.jpatest.set.SetBasicTestDataManipulator] (default task-8) find(): [hige, hoge, fuge]

Add

log

14:03:45,339 DEBUG [org.hibernate.SQL] (default task-15) select setbasic0_.id as id1_2_0_ from SetBasic setbasic0_ where setbasic0_.id=?
14:03:45,340 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [1] as [BIGINT] - [1]
14:03:45,341 DEBUG [org.hibernate.SQL] (default task-15) select set0_.SetBasic_id as SetBasic1_2_0_, set0_.set as set2_3_0_ from SetBasic_set set0_ where set0_.SetBasic_id=?
14:03:45,341 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [1] as [BIGINT] - [1]
14:03:45,345 DEBUG [org.hibernate.SQL] (default task-15) insert into SetBasic_set (SetBasic_id, set) values (?, ?)
14:03:45,345 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [1] as [BIGINT] - [1]
14:03:45,345 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-15) binding parameter [2] as [VARCHAR] - [hege]

table

jpatest=# select * from setbasic_set;
 setbasic_id | set  
-------------+------
           1 | hoge
           1 | hige
           1 | fuge
           1 | hege
(4 rows)

jpatest=#

Remove

log

14:05:08,367 DEBUG [org.hibernate.SQL] (default task-5) select setbasic0_.id as id1_2_0_ from SetBasic setbasic0_ where setbasic0_.id=?
14:05:08,368 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-5) binding parameter [1] as [BIGINT] - [1]
14:05:08,369 DEBUG [org.hibernate.SQL] (default task-5) select set0_.SetBasic_id as SetBasic1_2_0_, set0_.set as set2_3_0_ from SetBasic_set set0_ where set0_.SetBasic_id=?
14:05:08,369 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-5) binding parameter [1] as [BIGINT] - [1]
14:05:08,374 DEBUG [org.hibernate.SQL] (default task-5) delete from SetBasic_set where SetBasic_id=? and set=?
14:05:08,374 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-5) binding parameter [1] as [BIGINT] - [1]
14:05:08,374 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-5) binding parameter [2] as [VARCHAR] - [hige]

table

jpatest=# select * from setbasic_set;
 setbasic_id | set  
-------------+------
           1 | hoge
           1 | fuge
(2 rows)

jpatest=#

Set<Embeddable>

Schema

jpatest=# \d setembeddableparent
Table "public.setembeddableparent"
 Column |  Type  | Modifiers 
--------+--------+-----------
 id     | bigint | not null
Indexes:
    "setembeddableparent_pkey" PRIMARY KEY, btree (id)
Referenced by:
    TABLE "setembeddableparent_setembeddablechilds" CONSTRAINT "fk_r8ikgl74hjndujhjwuvnkt59m" FOREIGN KEY (setembeddableparent_id) REFERENCES setembeddableparent(id)

jpatest=# \d setembeddableparent_setembeddablechilds 
   Table "public.setembeddableparent_setembeddablechilds"
         Column         |          Type          | Modifiers 
------------------------+------------------------+-----------
 setembeddableparent_id | bigint                 | not null
 embfield1              | character varying(255) | 
 embfield2              | character varying(255) | 
Foreign-key constraints:
    "fk_r8ikgl74hjndujhjwuvnkt59m" FOREIGN KEY (setembeddableparent_id) REFERENCES setembeddableparent(id)

jpatest=#

Entry data

log

14:06:58,199 DEBUG [org.hibernate.SQL] (default task-12) insert into SetEmbeddableParent (id) values (?)
14:06:58,199 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [1] as [BIGINT] - [1]
14:06:58,200 DEBUG [org.hibernate.SQL] (default task-12) insert into SetEmbeddableParent_setEmbeddableChilds (SetEmbeddableParent_id, embField1, embField2) values (?, ?, ?)
14:06:58,200 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [1] as [BIGINT] - [1]
14:06:58,200 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [2] as [VARCHAR] - [child3field1]
14:06:58,201 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [3] as [VARCHAR] - [child3field2]
14:06:58,201 DEBUG [org.hibernate.SQL] (default task-12) insert into SetEmbeddableParent_setEmbeddableChilds (SetEmbeddableParent_id, embField1, embField2) values (?, ?, ?)
14:06:58,202 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [1] as [BIGINT] - [1]
14:06:58,202 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [2] as [VARCHAR] - [child2field1]
14:06:58,202 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [3] as [VARCHAR] - [child2field2]
14:06:58,202 DEBUG [org.hibernate.SQL] (default task-12) insert into SetEmbeddableParent_setEmbeddableChilds (SetEmbeddableParent_id, embField1, embField2) values (?, ?, ?)
14:06:58,202 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [1] as [BIGINT] - [1]
14:06:58,203 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [2] as [VARCHAR] - [child1field1]
14:06:58,203 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-12) binding parameter [3] as [VARCHAR] - [child1field2]

table

jpatest=# select * from setembeddableparent;
 id 
----
  1
(1 row)

jpatest=# select * from setembeddableparent_setembeddablechilds;
 setembeddableparent_id |  embfield1   |  embfield2   
------------------------+--------------+--------------
                      1 | child3field1 | child3field2
                      1 | child2field1 | child2field2
                      1 | child1field1 | child1field2
(3 rows)

jpatest=#

Find

14:10:32,579 DEBUG [org.hibernate.SQL] (default task-6) select setembedda0_.id as id1_4_0_ from SetEmbeddableParent setembedda0_ where setembedda0_.id=?
14:10:32,579 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-6) binding parameter [1] as [BIGINT] - [1]
14:10:32,580 DEBUG [org.hibernate.SQL] (default task-6) select setembedda0_.SetEmbeddableParent_id as SetEmbed1_4_0_, setembedda0_.embField1 as embField2_5_0_, setembedda0_.embField2 as embField3_5_0_ from SetEmbeddableParent_setEmbeddableChilds setembedda0_ where setembedda0_.SetEmbeddableParent_id=?
14:10:32,581 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-6) binding parameter [1] as [BIGINT] - [1]
14:10:32,580 FINE  [org.nailedtothex.jpatest.set.SetEmbeddableTestDataManipulator] (default task-6) [SetEmbeddableChild [embField1=child3field1, embField2=child3field2], SetEmbeddableChild [embField1=child2field1, embField2=child2field2], SetEmbeddableChild [embField1=child1field1, embField2=child1field2]]

Add

log

14:12:20,219 DEBUG [org.hibernate.SQL] (default task-13) select setembedda0_.id as id1_4_0_ from SetEmbeddableParent setembedda0_ where setembedda0_.id=?
14:12:20,220 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-13) binding parameter [1] as [BIGINT] - [1]
14:12:20,221 DEBUG [org.hibernate.SQL] (default task-13) select setembedda0_.SetEmbeddableParent_id as SetEmbed1_4_0_, setembedda0_.embField1 as embField2_5_0_, setembedda0_.embField2 as embField3_5_0_ from SetEmbeddableParent_setEmbeddableChilds setembedda0_ where setembedda0_.SetEmbeddableParent_id=?
14:12:20,221 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-13) binding parameter [1] as [BIGINT] - [1]
14:12:20,225 DEBUG [org.hibernate.SQL] (default task-13) insert into SetEmbeddableParent_setEmbeddableChilds (SetEmbeddableParent_id, embField1, embField2) values (?, ?, ?)
14:12:20,225 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-13) binding parameter [1] as [BIGINT] - [1]
14:12:20,225 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-13) binding parameter [2] as [VARCHAR] - [child4field1]
14:12:20,225 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-13) binding parameter [3] as [VARCHAR] - [child4field2]

table

jpatest=# select * from setembeddableparent_setembeddablechilds;
 setembeddableparent_id |  embfield1   |  embfield2   
------------------------+--------------+--------------
                      1 | child1field1 | child1field2
                      1 | child2field1 | child2field2
                      1 | child3field1 | child3field2
                      1 | child4field1 | child4field2
(4 rows)

Remove

log

14:14:48,499 DEBUG [org.hibernate.SQL] (default task-9) select setembedda0_.id as id1_4_0_ from SetEmbeddableParent setembedda0_ where setembedda0_.id=?
14:14:48,499 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-9) binding parameter [1] as [BIGINT] - [1]
14:14:48,500 DEBUG [org.hibernate.SQL] (default task-9) select setembedda0_.SetEmbeddableParent_id as SetEmbed1_4_0_, setembedda0_.embField1 as embField2_5_0_, setembedda0_.embField2 as embField3_5_0_ from SetEmbeddableParent_setEmbeddableChilds setembedda0_ where setembedda0_.SetEmbeddableParent_id=?
14:14:48,500 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-9) binding parameter [1] as [BIGINT] - [1]
14:14:48,500 FINE  [org.nailedtothex.jpatest.set.SetEmbeddableTestDataManipulator] (default task-9) [SetEmbeddableChild [embField1=child3field1, embField2=child3field2], SetEmbeddableChild [embField1=child2field1, embField2=child2field2], SetEmbeddableChild [embField1=child1field1, embField2=child1field2]]
14:14:48,505 DEBUG [org.hibernate.SQL] (default task-9) delete from SetEmbeddableParent_setEmbeddableChilds where SetEmbeddableParent_id=? and embField1=? and embField2=?
14:14:48,505 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-9) binding parameter [1] as [BIGINT] - [1]
14:14:48,505 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-9) binding parameter [2] as [VARCHAR] - [child1field1]
14:14:48,506 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-9) binding parameter [3] as [VARCHAR] - [child1field2]

table

jpatest=# select * from setembeddableparent_setembeddablechilds;
 setembeddableparent_id |  embfield1   |  embfield2   
------------------------+--------------+--------------
                      1 | child2field1 | child2field2
                      1 | child3field1 | child3field2
(2 rows)

jpatest=#

Update

log

15:07:27,811 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-7) binding parameter [1] as [BIGINT] - [1]
15:07:27,812 DEBUG [org.hibernate.SQL] (default task-7) select setembedda0_.SetEmbeddableParent_id as SetEmbed1_2_0_, setembedda0_.embField1 as embField2_3_0_, setembedda0_.embField2 as embField3_3_0_ from SetEmbeddableParent_setEmbeddableChilds setembedda0_ where setembedda0_.SetEmbeddableParent_id=?
15:07:27,812 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-7) binding parameter [1] as [BIGINT] - [1]
15:07:27,815 DEBUG [org.hibernate.SQL] (default task-7) delete from SetEmbeddableParent_setEmbeddableChilds where SetEmbeddableParent_id=? and embField1=? and embField2=?
15:07:27,815 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-7) binding parameter [1] as [BIGINT] - [1]
15:07:27,815 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-7) binding parameter [2] as [VARCHAR] - [child2field1]
15:07:27,815 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-7) binding parameter [3] as [VARCHAR] - [child2field2]
15:07:27,816 DEBUG [org.hibernate.SQL] (default task-7) insert into SetEmbeddableParent_setEmbeddableChilds (SetEmbeddableParent_id, embField1, embField2) values (?, ?, ?)
15:07:27,816 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-7) binding parameter [1] as [BIGINT] - [1]
15:07:27,816 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-7) binding parameter [2] as [VARCHAR] - [child2field1]
15:07:27,816 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-7) binding parameter [3] as [VARCHAR] - [child2field2-updated]

table

jpatest=# select * from setembeddableparent_setembeddablechilds order by embfield1;
 setembeddableparent_id |  embfield1   |      embfield2       
------------------------+--------------+----------------------
                      1 | child1field1 | child1field2
                      1 | child2field1 | child2field2-updated
                      1 | child3field1 | child3field2
(3 rows)

jpatest=#

Add a duplicate element

14:13:59,763 DEBUG [org.hibernate.SQL] (default task-14) select setembedda0_.id as id1_4_0_ from SetEmbeddableParent setembedda0_ where setembedda0_.id=?
14:13:59,764 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-14) binding parameter [1] as [BIGINT] - [1]
14:13:59,765 DEBUG [org.hibernate.SQL] (default task-14) select setembedda0_.SetEmbeddableParent_id as SetEmbed1_4_0_, setembedda0_.embField1 as embField2_5_0_, setembedda0_.embField2 as embField3_5_0_ from SetEmbeddableParent_setEmbeddableChilds setembedda0_ where setembedda0_.SetEmbeddableParent_id=?
14:13:59,765 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-14) binding parameter [1] as [BIGINT] - [1]

No changes are made to DB.

Remove a element that not exist

14:16:48,827 DEBUG [org.hibernate.SQL] (default task-10) select setembedda0_.id as id1_4_0_ from SetEmbeddableParent setembedda0_ where setembedda0_.id=?
14:16:48,828 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-10) binding parameter [1] as [BIGINT] - [1]
14:16:48,829 DEBUG [org.hibernate.SQL] (default task-10) select setembedda0_.SetEmbeddableParent_id as SetEmbed1_4_0_, setembedda0_.embField1 as embField2_5_0_, setembedda0_.embField2 as embField3_5_0_ from SetEmbeddableParent_setEmbeddableChilds setembedda0_ where setembedda0_.SetEmbeddableParent_id=?
14:16:48,829 TRACE [org.hibernate.type.descriptor.sql.BasicBinder] (default task-10) binding parameter [1] as [BIGINT] - [1]

No changes are made to DB.

Nested collection is prohibited

It said @ElementCollection can be used with embeddable or basic type only.

Conclusion

Pros

It works well as expected for some operations of Set API. it prevents that add duplicated elements.
It can reduce some annoying codes.

Cons

All elements are need to being fetched for manipulate, so maybe it is not good for large sets.
Child elements are not entities, so use of some convenient operations is impossible.

Remarks

Maybe it's good for proto-typing.
But I'm not sure about whether it is appropriate for production systems especially high-traffic concurrent systems.
For appropriate size sets, maybe 2nd level cache would be great help for its performance.

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Just try to use ElementCollection with Set

Environment

Example project

Set<Basic>

Schema

Entry data

log

table

Find

Add

log

table

Remove

log

table

Set<Embeddable>

Schema

Entry data

log

table

Find

Add

log

table

Remove

log

table

Update

log

table

Add a duplicate element

Remove a element that not exist

Nested collection is prohibited

Conclusion

Pros

Cons

Remarks

Leave a Comment

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